Moisture transport in impregnated concrete: Moisture Diffusion Coefficient, Modelling, Measurements and Verification
2006 (English)In: Journal on Restoration of Buildings and Monuments, Vol. 12, no 1, 13-24 p.Article in journal (Refereed) Published
In order to understand the mechanisms of water repellents it is important to have reliable data on how the moisture diffusion coefficient is affected by a hydrophobic treatment. The results from the experiment described below will be used as input data in a project aiming to create a computer model for simulations of moisture and material transport in impregnated concrete structures. Two types of concrete with wo /c = 0.8 and 0.45 have been investigated by means of the cup-method to determine the moisture diffusion coefficient. Half of the specimens have been completely impregnated with trietoxy(isooctyl)silane by capillary suction and the other half were left untreated. This silane is one of the most common used water repellents on the Swedish market. Four different saturated salt solutions are used to create a relative humidity (RH) between 85 % and 97 % inside the cups while the surrounding environment is kept at 50 % RH. Three cups for each situation, two cups with pure water and four cups for verification give a total of 54 cups. The weight of the cups has been monitored weekly until a constant weight loss per unit time is obtained. With the use of Kirchhoff's potential in the calculations, the cup method is an efficient way of measuring the moisture diffusion coefficient. The moisture diffusion coefficient for treated concrete is found to be close to constant and less influenced by the RH compared to untreated concrete. Further, the results have shown that the transport of water vapour is highly reduced after a water repellent treatment. The accuracy of the method is verified at conditions of low humidity and a one dimensional steady state flow.
Place, publisher, year, edition, pages
2006. Vol. 12, no 1, 13-24 p.
Water repellent treatment, Moisture diffusion coefficient, Cup-method, Kirchhoff’s potential
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-6301OAI: oai:DiVA.org:kth-6301DiVA: diva2:10979